Zimbra's products already have light file sharing and storage, but the capabilities aren't as robust as those in the Mezeo wares, said Patrick Brandt, CEO of Zimbra.

In addition, the file-sharing and storage components of Zimbra's existing products are hardwired and can't act as stand-alone storage repositories for other products. Moreover, the Mezeo products are architected to scale up for massive workloads.

Zimbra's goal isn't to compete against providers of cloud storage and file-sharing services like Box, Dropbox, Microsoft and Google, but rather strengthen its own collaboration suite.

"This Mezeo acquisition accelerates our road map," Brandt said.

Other areas he wants to solidify include security and mobility, whether via acquisitions or in-house development.

Zimbra sells few of its products directly to the customers that end up using them. Instead, it relies on managed service providers that white-label the products and in turn offer them on a hosted basis to their business and consumer customers. A smaller portion of its customer base buys its products from resellers and installs them on their own premises.

About 200,000 organizations use Zimbra products in 150 countries.

With the Mezeo deal, "we're arming our service providers and partners with the capability to offer this [storage and file-sharing] service to their customers, whether they're consumers or businesses," Brandt said.

His company was originally called Telligent, and its core product was the ESN suite. But a year ago, Telligent bought the Zimbra open-source email and calendaring system from VMware and changed its name to Zimbra.

The email server and the ESN suite have been integrated to an extent, and Brandt expects fusion of the products to be complete next year.

He declined to provide financial details of the Mezeo deal, which closed in early July.